Flat To Pitch Roof Conversions

Lightweight and easy to handle and fix, Decra tiles are ideal for flat to pitched roof conversions. Often no additional strengthening of the structure is required to support the Decra roofing system, as it is lightweight. Intricate detailing and installation on roofs even many storeys above ground, may be achieved quickly and cost effectively, reducing future maintenance requirements and enhancing the appearance of the building.

Why Convert?

Flat roofing is a tried and tested method of roofing a building. For centuries flat roofs have adorned all types of building from civil facilities, through industrial structures to residential buildings. Coupled with advances in materials and manufacturing technologies in the last 30 years, there has never been a better time to specify a flat roof.

There are scenarios where a flat roof is quite simply not the best solution. For example, a roof system that has been in place on a school building for many years, with inferior and decrepit components, may well have developed degradation problems that mean installing another modern flat roof system is not an economical or indeed viable option.

Flat to pitched roof conversion isn’t just the replacement of one type of roof for another. Instead, it allows re-modelling of the roof profile which, not only enhances the overall aesthetics of a building, but can also provide thermal benefits, enhance security and of course, improves surface water drainage. By installing such a system combined with a Decra tile, a pitched roof can achieve a life expectancy of up to three times that of a flat roof. 

  • Icopal Flat To Pitch Roof Conversions Explained

    Icopal’s flat to pitch roof conversion system consists of a frame which is bespoke to the roofing application utilising standard components, making it extremely easy to design and construct. Because FTP is made from steel, it is lightweight, high strength and 100% recyclable at the end of its working life.

    Flat To Pitch Roof Framework

  • From Flat To Pitch - The Process


    Project Before

    The existing flat roof covering was in a poor state of repair, suffering from ponding and water ingress, annual maintenance had not been carried out in line with flat roofing codes of practice. The building owner had a requirement to infill recessed areas to the front of the property. Flat To Pitch Conversion - Before


    Massing Study

    Icopal Technical Services can provide massing studies on request to give a clear indication of the finished roof profile that can be used for planning purposes. Flat To Pitch Conversion Massing Study


    Engineering Drawing

    Icopal will provide full engineering drawings and calculations for the roof to be constructed, which may be used to support building control and planning applications. Flat To Pitch Conversion Engineering Drawings



    Steel framework is quickly erected, the frame is light weight and resistant to insect and fungal attack. Flat To Pitch Conversion Framework


    Underlay & Battens

    Once the flat to pitch roof framework is in place Monarperm Breathe All Zones vapour permeable underlay is applied to the structure providing a water resistant covering, allowing the battens and ventilation system to be fixed prior to the installation of roof tiles. Flat To Pitch Conversion with battensnd underlay installed


    Completed Roof

    Pitched roof system completed using Decra Noxite Tile eradicating the need to maintain the roof annually and eliminating ponding on the roof surface. The flat to pitch roof design also allows over sail of the infill areas to better utilise balcony areas. Flat To Pitch Conversion After Completion


  • 5 Steps To A Succesful Flat To Pitch Conversion

    Icopal SecureAs the global leader in roof systems, Icopal offers comprehensive beginning-to-end project support to provide the strongest possible foundation for every flat to pitch roof conversion. Icopal is dedicated to providing the right balance of system performance, reliability and cost to help you meet the challenge of delivering best value. The Icopal Secure 5-Step Process ensures that we meet these objectives.

    1. Consultation and Site Survey

    We understand that each flat to pitch roof conversion project is different and it is vital for us to understand your requirements and expectations right from the outset. Refurbishment projects start with a comprehensive site survey including detailed analysis of the existing roof build up and condition. This information is critical to the correct specification and products being recommended.



    Our experienced team of Area Technical Managers are on hand to offer professional advice on all aspects of your project including:

    • The appropriate design for roof build up and building use.
    • Recommendation of the correct waterproofing system & associated products such as drainage and daylighting.
    • Interface detailing.
    • System performance and guarantee expectations.
    • Environmental impact.
    • Budget costing.
    • Planned maintenance schedules.
    • Drawings and calculations.
    • Regular feedback and project updates.
    • Site specific issues such as Occupancy, Schedules and Liaison.



    Surveys include a full roof condition report including where appropriate:

    • Roof measure & layout.
    • Roof falls & drainage items.
    • Rooflight replacement program.
    • Core samples to assess existing condition and roof build up.
    • Moisture probe analysis.
    • Photographic records.
    • Detailed assessment of roof failure mode and remedial options.
    • Roof details and interfaces.
    • Thermographic imaging where appropriate


    2. Design and Specification

    We provide a full design service including specifications, drawings and calculations, prepared in line with the Building Regulations and Codes of Practice. The quality of our products and comprehensive guarantees safeguard your project while our extensive knowledge and expertise means we can advise you on the correct system for your project. As a multi material supplier we can specify the most appropriate solution without bias, ensuring that it is the best fit for your specific project requirements.



    • Project Specific detail drawings showing critical elements such as interfaces and terminations.
    • Wind Uplift calculations in line with BS EN 1991-1-4/NA:2008.
    • Insulation Drainage: Our in house design team will prepare tapered insulation designs for effective roof drainage and thermal values in compliance with BS EN ISO 6946 Annex C.
    • U-Value & Condensation risk analysis. Icopal will recommend a solution to combat any potential threat of interstitial condensation.
    • Vapour Control & Airtightness. We supply a wide range of Vapour Control Layers & sealants to ensure the correct level of protection for your project.



    • The sooner we can become involved in your flat to pitch roof conversion project, the more effective we can be in helping you to achieve your expected outcomes of performance and cost.
    • A fully detailed specification package is prepared based upon your project criteria and our detailed analysis and submitted for your consideration in either long form using Specmaster or short form NBS format


    3. Installation

    Our approved specialist contractors carry out all installations and ensure that from the outset, work is completed efficiently and to specific qualitative standards. All our accredited contractors have undergone comprehensive and specific training at one of Icopal’s training centres. The installation process includes a pre-commencement briefing with your contractor, a full overview of the specific requirements and features of the roof detailing. Icopal can even arrange for unique mock-up structures of key detailing elements to be created so that all involved can rehearse and prepare beforehand.


    4. Site Support and Project Monitoring

    Our site technicians are regularly on site to closely monitor progress and ensure the project runs smoothly, focusing on any potential drift from specification, quality of workmanship and aesthetic condition. Through their expertise and practical approach they offer technical advice and support throughout the project and beyond, with detailed site reports issued following each visit and a final inspection to confirm your satisfaction and sign-off.


    5. System Guarantee

    Our guarantees are comprehensive and industry leading. We support our systems with single point responsibility covering product, workmanship, design and consequential damage. We carry annual product guarantee insurance which is arranged with first class security in the London Insurance Market and are the only waterproofing manufacturer regulated by the Financial Conduct Authority (FCA). This is our confirmation that we operate with integrity and provide the financial strength of a global market leader. Most importantly that we have our customers best interests at heart.


  • Icopal Flat To Pitch Components



    Application: Used to support overhangs or as cladding rails on gables.

    Flat To Pitch Component - TH45


    Application: Used as TH45 in instances where additional strength is required such as longer spanning or higher load situations.

    Flat To Pitch Component - TH85

    50 / 50 Angle

    Application: To provide lateral bracing between supports.

    Flat To Pitch Component - 50-50-Angle


    Application: To form the top member of the adjustable prop.

    Flat To Pitch Component - Insert

    50/50/50 Zed

    Application: To form the base member base member and rafter.

    Flat To Pitch Component - 50-50-50-Zed


    Application: To form the base of an adjustable prop and also can be used for bracing.

    Flat To Pitch Component - Sleeve
  • Downloads

    On this page you can download our information and documentation in one place. Click on any of the acrobat icons below and the brochure will start to download.


    download pdf Icopal Flat To Pitch Roof Conversions (ICO3243)
    download pdf Decra Brochure - (ICO2371)


Contact Us

To discuss your flat to pitch roof conversion needs we can arrange for one of our local Regional Sales Managers to contact you. Just call our Decra’s Sales Support and Technical Services team on

                   0161 8654444

or fill in the form below with your details and we will be in contact with you shortly.

When is the roofing works scheduled to commence?

Contact Us

Contact Us

To discuss your project in more detail please contact
Your Local Area Manager


Technical Support


0330 123 4585

Email: technical.uk@bmigroup.com


Sales Enquiries & Orders


0843 224 7400


0843 224 7401

Email: sales.admin@bmigroup.com

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